Logo Tropentag

Tropentag, September 10 - 12, 2025, Bonn

"Reconciling land system changes with planetary health"


Elite bradyrhizobium markedly enhanced symbiotic N2 fixation towards yield advantage in cowpea: An option for sustainability

Tewodros Dejene1, Tarekegn Yoseph Samago1, Georg Cadisch2

1Hawassa University, College of Agriculture, Plant & Horticultural Sciences, Ethiopia
2University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Germany


Abstract


Due to its N2-fixating capacity, cowpea contributes much to production and soil sustainability in resource limited tropical regions. However, its symbiotic N contribution and yield frequently remained low under field circumstances, in part because of the restricted application and ineffectiveness of bio-inoculants. Therefore, using a factorial randomised complete block design with four replications, a two-year field experiment was carried out to assess the effect of cowpea infecting Bradyrhizobium strains (CP-24 and CP-37) on shoot biomass and symbiotic N nutrition of four cowpea varieties (Keti, TVU, Black eye bean, and White wonderer trailing) at three sites. The N contribution was calculated using the 15N natural abundance. Inoculating cowpea markedly increased shoot biomass, nodulation, % Ndfa and amount of N2 fixed, indicating the symbiotic efficiency of the Bradyrhizobium straints used. Compared to the un-inoculated control, inoculation with CP-24 strain increased shoot N content, % Ndfa and N fixed by 40%, 15%, and 41%, respectively. In addition, the inoculant by variety interaction also had a significant effect on nodule number, nodule dry weight and N fixed, with paramount advantage from TVU and White wonderer trailing combination with CP-24. A strong positive correlation between biomass accumulation and N2 fixed, and N2 fixed and seed yield was also observed. In general, inoculation of varieties TVU and White wonderer trailing with CP‐24 Bradyrhizobium strain is recommended at all the three tested sites and similar agro‐ecological environments for improved symbiotic N nutrition and associated yield advantage of cowpea as these combinations outperformed the response from Keti and Black eye bean varieties combination with either of the two strains.


Keywords: % NDFA, cowpea, N2 - fixation, nitrogen content, sustainability, symbiosis


Contact Address: Tewodros Dejene, Hawassa University, College of Agriculture, Plant & Horticultural Sciences, Hawassa University, 05 hawassa University, Hawassa Hawassa, Ethiopia, e-mail: tednet2011@gmail.com


Valid HTML 3.2!